cymcsg/UltimateRecyclerView

Recyclerview in a PageView

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#395 opened on Jul 6, 2016

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help wanted

Description

I am having a problem implementing multiple recyclerviews inside a pageview. I have multiple fragments representing each page in a pageview. Each fragment implements its own unique ultimate recyclerview.

Here is the error: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.ClipData.getItemCount()' on a null object reference at android.widget.Editor.onDrop(Editor.java:2153) at android.widget.TextView.onDragEvent(TextView.java:9566) at android.view.View.dispatchDragEvent(View.java:19700) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewGroup.dispatchDragEvent(ViewGroup.java:1518) at android.view.ViewRootImpl.handleDragEvent(ViewRootImpl.java:5282) at android.view.ViewRootImpl.-wrap6(ViewRootImpl.java) at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3457) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

An internet search indicates the error may be caused by failure to wrap the recyclerview inside a LinearLayout. But I have done that in the xml layout file as well as in code: ultimateRecyclerView.setLayoutManager(new LinearLayoutManager(ultimateRecyclerView.getContext()));

The error occurs when drag and drop is performed on device. The error is random. Cannot detect a drag/drop pattern to make error occur.

Please help.

Contributor guide

Tech stack
javaandroid
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
Android RecyclerViewPageViewFragments
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Examine the UltimateRecyclerView source code, especially drag and drop handling in RecyclerView. The error stack trace indicates a NullPointerException in Editor.onDrop, suggesting a TextView's drag event handler is failing. Check if there are any known issues with RecyclerView inside ViewPager in this library. Also, consider whether the drag event is being consumed properly by the RecyclerView's item decorators or if the LinearLayout wrapper is insufficient. Look at issue #395 and search for similar reports in the repository.